The present invention relates to clutches in general, and more particularly to improvements in clutch plates (also called driven discs) which form part of friction clutches and serve to transmit torque from a rotary driving member (e.g., the flywheel which receives torque from the crankshaft of the engine in an automotive vehicle) to a rotary driven member (such as the splined input shaft of the transmission in an automotive vehicle). Still more particularly, the invention relates to improvements in clutch plates of the type wherein a driving unit (including the part or parts which receive torque from the rotary driving member) transmits rotary motion to a driven unit (including the part or parts which transmit torque to the rotary driven member) by way of one or more helical springs or other suitable energy-storing torque transmitting devices. As a rule, the driving unit includes one or more friction linings or discs which are engaged by the customary pressure plate and/or flywheel when the clutch transmits torque, and the driven unit includes a hub which is movable axially of but cannot rotate with respect to the rotary driven member. The torque transmitting device or devices can undergo a certain amount of deformation when the driving unit tends to rotate relative to the driven unit and thereupon ensure that the driven unit shares the angular movements of the driving unit.
It is also known to provide a clutch plate of the above outlined character with a means (hereinafter called damping device or insert) which is disposed between the driving and driven units and serves to perform a damping action during that stage of angular movement of the driving unit when the latter rotates relative to the driven unit against the opposition of the yieldable torque transmitting means or while the torque transmitting means dissipates energy to change the angular positions of the two units with respect to each other. The damping device is of annular shape and exhibits at least some elasticity, as considered in the axial direction of the clutch plate.
A clutch plate with yieldable torque transmitting means and a damping device is disclosed in British Pat. No. 1,174,692. The hub of the driven unit of the patented clutch plate has a flange which is disposed between two annular components of the driving unit, namely, a disc-shaped carrier member for one or more friction linings at one side and a disc at the other side of the flange. The carrier member is connected with the disc by several rivets. The rivets ensure that the carrier member and the disc rotate as a (driving) unit which is coupled to the driven unit (including the hub and its flange) by the aforementioned torque transmitting devices in the form of prestressed helical springs or the like. When the flywheel rotates the driving unit relative to the driven unit, the springs store additional energy before the driven unit begins to share all angular movements of the driving unit. Friction generating washers are installed between the sides of the flange of the hub on the one hand and the carrier member and disc of the driving unit on the other hand. These washers perform a damping action when the driving unit turns relative to the driven unit and/or vice versa. Friction is generated owing to the provision of a dished spring which reacts against the aforementioned disc of the driving unit and bears against the washer which is interposed between the disc and the flange. The dished spring rotates with the disc of the driving unit; to this end, the dished spring has radially outwardly extending arms, the radially outermost portions of which are bent to positions of substantial parallelism with the axis of the hub and extend into openings provided therefor in the disc of the driving unit.
A drawback of the damping device in the clutch plate of the aforementioned British Pat. No. 1,174,672 is that it comprises several discrete parts, namely, the washers and the dished spring. This contributes to initial cost of the clutch, and the assembly of such discrete parts with the driving and driven units of the clutch plate takes up a substantial amount of time. Moreover, the combined thickness of the components of such damping means (as considered in the axial direction of the clutch plate) is quite pronounced so that a clutch plate embodying the just described conventional composite damping device cannot be used in all types of friction clutches. More specifically, many types of clutch plates do not provide enough room between the carrier member and the disc of the driving unit to allow for introduction of the flange (of the driven unit), one or more friction generating washers as well as a dished spring.